Tnt composition containing a cellulosic resin which is free from oily exudation upon storage

ABSTRACT

A castable high explosive composition of the 2, 4, 6trinitrotoluene (TNT) variety containing a cellulosic resin having a thermoplastic nature. A method of incorporating a thermoplastic resin of the cellulosic variety into a castable high explosive composition containing TNT by initially coating such cellulosic resin on the surface of a finely divided solid explosive and then uniformly dispersing the latter throughout the castable composition.

United States Patent 1151 3,706,609

Voigt, Jr. et al. 1 Dec. 19, 1972 s41 TNT COMPOSITION CONTAINING A2,814,570 11/1957 Sloan et al. ..106/170 x CELLULOSIC RESIN WHICH ISFREE 2,966,405 12/1960 Sloan et al 149/60 x 3,290,190 12/1966 Godfrey etal.... ..l49/18 EXUDATION UPON 3,403,061 9/1968 McDonald ...149/18 X3,523,841 8/1970 Knight ..l49/94 X [72] Inventors: H. William Voigt,Jr., Stanhope,

N Lawrence n w Primary ExaminerCarl D. Quarforth Orange, N 1; JeanPicard, Assistant Examiner-P. A. Nelson i N J Attorney-Harry M.Saragovitz, Edward J. Kelly and Herbert Ber] [73] Assignee: The UnitedStates of America as represented by the Secretary of the ABSTRACT Army Acastable high explosive composition of the 2, 4, 6- 22 Filed; 29,1970trinitrotoluene (TNT) variety containing a cellulosic resin having athermoplastic nature. [21] Appl. No.: 102,541

A method of incorporating a thermoplastic resin of the cellulosicvariety into a castable high explosive [52] US. Cl. ..l49/18, 149/105,149/107, composition containing TNT by initially coating Such 149/99cellulosic resin on the surface of a finely divided solid [51] Int. Cl...C06b 9/04 explosive and then if ly dispersing the latter Fleld ofSearch 1, 18, 19, 94, 99, throughout the castable compositior 7 Claims,No Drawings [56] References Cited UNITED STATES PATENTS Sloan etal....., ..106/l82 X TNT COMPOSITION CONTAINING A CELLULOSIC RESIN WHICHIS FREE FROM OILY EXUDATION UPON STORAGE The invention described hereinmay be manufactured, used and licensed by or for the Government forGovernmental purposes without the payment to us of any royaltiesthereon.

This invention relates to an improved castable high explosive of the TNTvariety.

More particularly, this invention relates to a castable high explosivecomposition containing TNT which has been modified with a thermoplasticresin of the cellulosic variety.

As is well known, castable high explosives are not only required in themanufacture of large caliber shells, bombs and land mines but are alsopreferred in the manufacture of other type shells due to simplicity inhandling, safety achieved in loading and overall cost in manufacture.

In the past, characteristics such as exudation, voids, brittleness andirreversible expansion were noted in the preparation of a castable highexplosive such as TNT. In the case of exudation, the low meltingoilsusually appear when the castis stored around 71 C. but may appeareven at room temperature. This leads to loose charges and possiblepremature explosions in the gun barrel. Also, the physical nature of thecast is usually brittle, particularly at the low temperatures requiredby military use, and cracking occurs where the cast is cycled fromdiffering zones of temperature. The latter condition ultimately affectsthe impact sensitivity of the cast, and can reduce the penetration ofarmor plate by shaped charges. Furthermore, the coefficient of thermalexpansion of this type castable explosive is high, and irreversibleexpansion of the cast occurs when heated. This facilitates the formationof voids which also adversely influences the impact sensitivity of thefinal cast.

In the past, additives of the silica variety having a finely dividedparticulate nature were utilized as absorbents of the low melting oilswhich usually make up the bulk of the exudation of the explosive cast.However, as is well known, undesirable cracks with their inherenthazardous characteristics usually develop in the solidified explosivecast when such additives are added to the initial composition containingTNT. Another difficulty encountered in the use of this system lies inthe fact that silica usually possesses some degree of absorbed waterwhich also interferes with the final characteristics of the solidifiedexplosive cast. For instance, calcium silicate, a commonly used additivewhich is alkaline, reacts with the TNT to produce a dark brown explosivecast having a relatively higher sensitivity to impact. It may be furtherstated that the use of this additive system disadvantageously affectsthe cast explosive with respect to brittleness, and cracking duringtemperature cycling.

In a recent innovation in the art, a therrnosetting elastomer was addedto the initial explosive composition utilized to produce a castexplosive in order to overcome the difficulties of the aforesaid system.However, as described in patent application titled lmproved CastableExplosive," Ser. No. 610,697 dated Jan. 20, 1967, this thermosettingmodification of the cast binds the TNT in such a manner during curingthat the scrap resulting from the conventional loading operation cannotbe remelteduniformly or readily reused. This scrap is the portion of theexplosive cast above the main portion when the cast is cooled tosolidify the fluid composition after loading into a shell.

However, this difficulty is quite important because the individualclasses of weapons utilizing various cast explosive compositions basedon TNT number in the hundreds. These requirements are of a continuingnature by the military and are especially acute during periods ofnational emergency. Therefore, if the scrap which represents about 10percent of the volume of explosive utilized in a single castingoperation were available foreffective reuse, tremendous savings wouldresult coupled with a more efficient manufacturing process to offset theeffect of acute shortages of the prime ingredients of the explosive castduring such times of national emergency.

What is needed is a castable explosive of the TNT variety whoseexplosive cast is amenable to processing with enhanced efficiency as aresult of the ability of the cast to be effectively and totally utilizedon a repetitive basis. In addition, such explosive cast should be freeof voids, cavities and exuding oils and should possess, from a militarypoint of view, an improved degree of sensitivity to impact shock besidesother characteristics which advantageously affect brittleness and thefurther ability of the cast to be recycled from differing zones oftemperature.

The subject invention answers the needs of the art with the eliminationof the aforesaid disadvantages in the manufacture of explosives of theTNT variety with special emphasis on an explosive charge of a remeltablenature, whose solidified cast is homogeneous with improved sensitivityto impact and freedom from such troublesome characteristics such asexudation, cracks and brittleness.

It is therefore an object of this invention to provide an improvedcastable high explosive of the TNT variety having characteristics whichmake it amenable to reprocessing on a repetitive basis for theproduction of an optimum number of casts from a single batch possessingan acceptable level of quality within controlled limits.

Another object is to provide a castable high explosive of the aforesaidtype possessing, in addition, freedom from voids, cracks, and exudationand having an acceptable level of sensitivity to thermal cycling andimpact.

A further object of this invention is to provide a castable highexplosive of the TNT variety modified with an additive system containinga thermoplastic resin which may be effectively and totally utilized inthe loading operation.

A further object is to prepare a castable high explosive from a crudegrade of TNT rather than from the refined grade of TNT conventionallyemployed, thereby eliminating the costly treatments and pollutionproblems attending such purification of TNT.

A still further object of this invention is to provide a method enablingthe advantageous addition of selected thermoplastic resins to such highexplosives to achieve the aforesaid characteristic in a simple, easy andefficient manner amenable to the use of conventional techniques ofmanufacture.

Other objects and many of the attendant advantages of this inventionwill become better understood upon a reading of the following detaileddescription, wherein:

Broadly, the composition of this invention encompasses a castable highexplosive of the TNT variety modified with a thermoplastic resin of thecellulosic variety, preferably having explosive characteristics.

More specifically, in the preferred embodiment, this invention relatesto the modification of a castable composition of TNT with a highmolecular weight cellulose nitrate, also known as nitrocellulose. Theselected cellulose nitrate is a very durable, heat-resistant materialhaving a nitrogen content of about 12 percent and a viscosity of 600 to1,000 RS seconds. in this manner, the heat stability of the basicexplosive composition can be maintained without compromise.

The composition of this invention is based on the concept that the highmolecular weight nitrocellulose has the propensity to accept the lowmelting impurities of the composition, such as dinitrotoluene andmononitrotoluene, as well as, unsymmetrical isomers of trinitrotoluene,all of which contribute to the exudation of the cast. As a result ofsuch substantially high uptake in this regard, relatively small amountsof the nitrocellulose are necessary to prevent exudation of the cast.Thus, the viscosity of the melt is not appreciably altered by theaddition of such cellulosic additive and the pourability of thecomposition is maintained. It has also been found that by such additionof the cellulosic material, an explosive cast is achieved having greatermechanical strength and enhanced heat resistance.

There are other cellulosic type of thermoplastic resins which may beused to advantage in the present composition and these include celluloseacetate, cellulose acetate butyrate, ethyl cellulose, modified cellulosenitrate, e.g., cellulose acetate nitrate, cellulose propionate andcellulose nitrates of viscosities other than that specified for thepreferred embodiment.

in general, the castable explosive composition must possess a relativelylow viscosity in order to be effectively poured or cast into a shellwith an acceptable efficiency of operation. However, the incorporationof the selected high molecular weight nitrocellulose does not noticeablyincrease the viscosity of the melt and the resulting solidified castexplosive is extremely homogeneous in nature. We have found that thecellulosic additive may be uniformly incorporated into the castableexplosive composition in an amount between about 0.1 and 2.0 percent byweight based on the weight of the TNT present in the composition withoutencountering any of the aforesaid difficulties of the art. However,highly satisfactory results have been achieved when as little as about0.6 percent of the preferred cellulosic material was added to thecomposition. In fact, the latter modified composition containingcellulose nitrate was so stable with regard to heat that substantiallyno liberation of gas occurred when a gram sample of such modifiedcomposition was tested for 40 hours in the standard 120 C. vacuumstability test.

in a preferred embodiment of this invention the thermoplastic cellulosicresin additive is employed together with an organic plasticizertherefor. It has been found that the use of an organicplasticizer-cellulosic additive system is more effective for physicallybinding and taking up the liquid impurities present in TNT and therebyreduces exudation more effectively than use of the cellulosic additivealone. Organic plasticizers for thermoplastic cellulosic resins used asadditives in this invention are well known. illustrative organicplasticizers which may be used include esters of-organic and inorganicacids, such as acetylated castor oil, diethyl phthalate,dibutylphthalate, octyl descylphthalate, dioctyl succinate, dibutylsebacate, dihexyl sebacate, dihexyladipate, and tris (dichloropropyl)phosphate.

Advantageously, the selected nitrocellulose may be uniformlyincorporated into the TNT composition by precoating which term in thisinvention includes intimately mixing a finely divided solid, preferablyan explosive compound, with such selected cellulosic material, and thendispersing the coated finely divided solid throughoutthe TNT melt priorto the pouring and solidification of the resulting composition in ashell. The finely divided solids which may be utilized for this purposeinclude pentaerythritol tetranitrate, cyclotrimethylene trinitramine,cyclotetramethylene tetranitramine, ammonium nitrate, crystalline TNT,aluminum powder and finely divided organic resins. If desired, toimprove the heat stability, of the nitrocellulose, a plasticizer for thenitrocellulose of the epoxy variety may aiso be coated on the finelydivided solid along with the nitrocellulose or added directly to the TNTmelt. In addition, the use of such particulate solids with thenitrocellulose also contributes to the degree of heat stability of theselected nitrocellulose. it has been found that substantially uniformdistribution of the selected cellulosic material throughout the entiremelt is is achieved by this simple method.

Precoating in said manner may be omitted in certain instances as in thecase of commercial TNT compositions which contain substantial amounts ofanother particulate explosive such as HMXJn such case when thenitrocellulose additive in powdered form is sprinkled into the agitated,molten TNT, the particulate explosive already present functions asacarrier to disperse the nitrocellulose additive in the molten TNT. Thispermits the nitrocellulose to colloid or gel rapidly and uniformlythroughout the molten mass and thus minimize its tendency to separateand rise to the surface as a separate layer or blobs.

The following is a procedure which has proved itself to be highlysatisfactory in the coating of the finely divided explosive with thecellulosic material of a thermoplastic nature, prior to the addition ofsuch coated explosive to the melt containing trinitrotoluene.

PROCEDURE A colloidal nitrocellulose lacquer was added to a slurry ofthe crystalline explosive and the resultant mass was agitated by mixingfor about 20 minutes. The lacquer contained 11.2 lbs. of a solvent suchas methyl ethyl ketone in which was distributed 0.6 lbs. ofnitrocellulose plasticized by 0.6 lbs. of an epoxy plasticizer. Thespecific nitrocellulose utilized was initially wet with ethanol andpossessed a viscosity of about RS 890 seconds and contained about 11.81percent nitrogen. The epoxy plasticizer was of the epoxidized soy beanoil variety but satisfactory results were also achieved withpentaerythritol tetraepoxystearate. The slurry of the crystallineexplosive contained 18.8

lbs. of fine beta cyclotetramethylene tetranitramine having a particlesize of about 5 to microns distributed in 8 lbs. of water containing0.01 grams of polyvinyl pyrrolidone.

molecular weight nitrocellulose are required to combine with the liquidplasticizers present in the melt to produce a tough, impact resistant,elastomeric film having explosive characteristics. In fact, suchpreferred After the resultant mass was thoroughly mixed, the 5nitrocellulose has been found to combine physically supernatant liquidwas removed by filtering or decantawith the plasticizers in an amount ofup to 500 percent tion. At this point, 40 lbs. of cold water was addedand by weight based on the weight of the nitrocellulose, the agitationwas continued for about 2 minutes after latter absorbing plasticizers ofthe epoxy variety plus which the suspension was filtered and the filtercake the low melting liquid impurities of the explosive cast was washedat least twice with individual portions of such as dinitrotoluene andmononitrotoluene as well as about 25 lbs. of cold water. The resultingsuspension the unsymmetrical isomers of the melt itself. was thenfiltered and the precipitate was dried at 70 C. in a further embodiment,conventional uncoated to a moisture content of about 0.1 percent. finelydivided explosives may also be suspended in the The product of thisprocedure was found to produce 1 5 melt and the resulting cast. However,to insure an negligible amount of gas in the Standard Vacuum completesuspension of such crystalline explosive, Stability test at 120 C. for40 hours. hydrophobic silica of the precipitated variety having a Afterthe crystalline explosive is coated with the celmicrofine particle sizeis added to the melt. Usually, the lulosic material, the resultingproduct is distributed use of silica imparts cracking to the cast.However, we throughout the melt of trinitrotoluene prior to loading havefound that if i to 2 percent of hydrabietyl alcohol in order to furnisha nitrocellulose content of about 0.6 is added along with the silica,cracking will be percent uniformly throughout the melt. For example,prevented and the bonding of the crystalline explosive only about 20parts of the product of said procedure to the basic explosive cast willbe enhanced. However, ne d b dd d t b t 30 pal-[S f h l to insure if itis de-sired to eliminate the silica in such addition of the requiredamount of nitrocellulose. However, since crystalline expbsive, it hasbeen found highly desirable i i common to incorporate 1 part f h b i lto vibrate the melt containing the crystalline explosive intoapproximately 3 parts of filler of the crystalline exto purposely causesuch crystalline explosive to Seine plosive variety, only about 0.2parts of the product of throughout the c In c a case, a highercrystalline Said procedure is necessary to prevent exudation andexplosive content is achieved than IS possible with ordicracking of thefinal cast through the action of the nary techniques" nitrocellulosa inany case, our concept functions according to the As an alternate to theabove procedure, a finely diq'i of TNT present}? a given cast explosivecomposition and therefore, it 18 only necessary to add that videdcoprecipitate could be prepared containing ap- Mose to quantity of ourthermoplastic additive to the melt proxlmately 30 percent by of mtiocerequired and based on the actual trinitrotoluene 70 pefcent of acrystalhile. exgloswe such as present in the melt. The amount and natureof the finecyclommethylene .mmiramme and ly divided solid explosivefiller may be essentially disrecyclotetramethylene tetranmamme' only 2pints of garded, since the trinitrotoluene which furnishes thesuchproduct added to 98 parts of TNT.are reqliued to characteristics ofpourability and castability to the melt Provld? a content of percent byweght of mtmcel' 0 also is the ingredient possessing the properties ofbritlulosem the melt tleness and the tendencies to crack and exude, the

Thus, it is Possible to Produce an cXPIOSiVB melt 0f latter propertiesthis invention is designed to correct. e trinilromluelle v rie y a g e se 0 Table I, which follows, illustrates a preferred series viscosity orpourability necessary in casting, in addition f f m las for thecomposition of this invention and to producing the desired mechanicaland phys a the inherent advantages of this system may be readilycharacteristics in the resultant solidified cast. This is appreciated bycomparing its properties to that of 21 achieved because very smallamounts of the high control which is also shown.

TABLE I Ingredients 1. HMX or RDX filler 2. TNT 3. High molecular weightN 4. Epoxy plasticizer 5. Hydroabietyi alcohol... 00 6. Hydrophobicsilica 0. 20 0. 20 0. 15 Characteristics:

120 C. vacuum stability, 40 hrs. 5 gm. ml. gas. 0. 70 Negligible.-.

P.A. impact sensitivity, 2 kg. wt., ht., inches. 17

Friction pendulum sensitivity tes Unaffected- Unafl'ectetL- Unaffected"Unafiect Unafiected. Pourabiiity of melt Very good.-. Satisfactory- Verygood... Satisfactory Satisfactory. Hardness of cast, Shore Durometer C.D57, non-brittle D45, brittle.

D50, no exuding Exudes.

-40 C D60, no cracking Cracks, brittle. Suspension of HMX or RDX fiilcrComplete-.. Complete. Complete--. Obtained by vibrating.selggggtiorfiafigisettiing of Temperature cycling, C to +71 CUnaffected- Unaflectei. Unaffected. Unaffected Brittieness, exudation,and

irreversible growth accompanied by cracks Y in cast. Uniformity ofdistribution of TNT impurities. Complete..- Complete.-. Complete...Complete Iniegmpliete; exuding of pur ties. 71 0. storage No eiicct.. Noeifect.... No effect.... No reflect. Exuding. Overall ciicctivothermoplastic plasticizution l0 ..10 6. 9.... 7.2.." None.

of TNT contont, percent. ()vcrnll NC content; relntivc to TNT, percent.0.61 1. 2 0. 59 0.57 Do.

\ Percent by weight based on weight of total composition 1. HMXcyclotetramethylene tetranitramine RDX cyclotrimethylene trinitramine 2.TNT 2, 4, 6 trinitrotoluene 3. High molecular weight nitrocellulose: RSGOO-1,000 seconds of approximately 12 percent nitrogen content. RS is aviscosity measurement in seconds by the Hercules standard method whichuses a 16 ounce solution or 12.2 percent solution of nitrocellulose in a3.1 butyl acetate: ethanol solvent mixture.

4. Epoxy plasticizer: an epoxidized plasticizer which may be selectedfrom the following group:

a. Pentaerythritol tetraepoxystearate having a pour point of 20F,oxirane oxygen content of 5.4 percent and iodine number of 1.1.

b. Triglyceride of stearic acid containing epoxy and acetoxy groups.

c. Epoxidized soy bean oil having a pour point 15F, oxirane oxygen of6.8, and iodine number of 2.0.

5. Hydroabietyl alcohol, technical grade: a high molecular weight, ofapproximately 274, monohydric alcohol, which may have various degrees ofhydrogenation such as dehydro-, diand tetra-, which is made from rosinacid or abietic acid by reduction of the carboxyl group to an alcohol.This material is a viscous liquid at room temperature, having a hydroxylvalue of approximately percent, acid number about 0.3, and is misciblein TNT.

6. Hydrophobic silica: a microfine, precipitated silica powder preparedin manufacture whereby approximately percent of silicone oil (hydrogenmethyl siloxane) is cured at 300 C. for 16 hours with fine silica toform a silicone-bonded silica of negligible internal porosity, ofapproximately millimicron ultimate particle size, which coated productis a thermal and hydrolytic-stable material used to suspend materialswithout unduly increasing viscosity of the system.

In an another embodiment of this invention, enhanced heat resistance inlong term storage of the cast may be achieved when a powderedthermoplastic resin such as cellulose propionate is utilized as theadditive plus a specified plasticizer such as acetylated castor oil,di-n-hexyl azelate or dibutyl sebacate, each of which functions todecrease or prevent the brittleness of the cast at temperatures as lowas 40 C. The addition of an epoxy resinous liquid such as the bisphenoltype acts as a heat stabilizer for the cellulose propionate.

A preferred example of cellulose propionate as an additive for use inthe present composition follows.

EXAMPLE Ingredients grams 1) TNT 68 2) 1 part TNT to 3 parts RDX 126 3)Silicone antifoam liquid 0.0133 4) Epoxy resin 0.133 5) Cellulosepropionate powder 0.800 6) Fibrous rovings of Polyethylene terphthalate0.267 7) Di-n-hexyl azelate 0.267

A cast produced from the above composition contained about 2.1 percentof the thermoplastic additive based on the weight of the trinitrotoluenepresent in the system and was found to be highly effective for use inlong burster tubes with the attendant advantages heretofore enumerated.

Other examples of the use of cellulose propionate as the thermoplasticadditive of this invention are set forth A powdered cellulose esterresin having about 65.5% combined acid as propionic acid and having afalling ball viscosity (ASTM D871-56) of about 10 seconds. The averagemols per glucose unit are 2.35 propionate, 0.40 acetate and 0.25hydroxyl.

Note: 0.10 parts of Dacron fibrous rovings of 0.5 denier (141 inchlength) may be added to the above to increase strength and lower thermalexpansion of the cast.

The thermoplastic cellulose resins and plasticizers may be included inthe composition up to a total of about 15 percent by weight based on theweight of the trinitrotoluene-1t has been found that as the content ofthe cellulosic material is increased relative to the content of thetrinitrotoluene and as the content of the specified liquid additives isdecreased, the pour viscosity of the melt increases. In general, a lowviscosity melt is desirable to achieve a practical pourability beforesolidification of the cast.

As is evident from the foregoing, this invention produces a castableexplosive of the modified TNT variety whose solidified cast ishomogeneous and remeltable for reuse in addition to being free ofexuding oils or cracks, less brittle and with the ability to withstandtemperatures ranging from 50 C. to 71 C. Included is a method ofincorporating a thermoplastic resin in the explosive composition toaccomplish these advantageous results as well as a means of suspendingparticulate explosives throughout the basic explosive cast. Thisinvention obviates the disadvantages of the art while also improving themechanical strength and toughness of the basic cast explosive byimparting a somewhat elastomeric property to the cast in order todecrease brittleness particularly at temperaturesas low as --50 C. whilepreventing undesirable exudation from the cast at temperatures as highas 71 C.

This invention is of an unexpected nature because when ordinary lintersor fibers of nitrocellulose are added to the melt, they will not readilydistribute but will rather clump or rise to the surface. Furthermore,the means of incorporating such thermoplastic resins of the cellulosicvariety into the cast provides a way of making optimum use of the scrapfrom ordinary loading.

This invention is also advantageous from an economic point of view. Thescrap from the ordinary loading may now be remelted and reused withincontrol levels as to quality because they will not deviate in chemicalanalysis from any other portion of the solidified cast. This is becausethe low-boiling, less fully nitrated fractional impurities of the castare uniformly distributed because they have plasticized thethermoplastic resinousadditive. This is in contrast .to the ordinarycast of trinitrotoluene where the scrap materia1 is not uniform incomposition making for a less perfect explosive cast if ever reused.

Also, the end product of this invention consisting of the presentcomposition is of a pourable nature. This is further unexpected becauseif a low viscosity, less heat stable nitrocellulose were added to themelt to achieve any of the aforesaid advantages, it would require anexcessive amount of additive resulting in an excessively viscous melt.

Another important advantage of the invention is that it reducespollution of environment by utilizing lowgrade TNT in place ofconventional purified TNT. This obviates the final stage of TNTmanufacture, viz. treatment with aqueous sodium sulfite before washingand drying, and eliminates the burning of nitrous oxides in theatmosphere and discharge of red-colored aqueous effluents into streams.

What is claimed is:

1. A castable explosive composition which is free from oily exudationduring storage comprising 2,4,6-trinitrotoluene and 0.1-2.0 percentbased on the weight of said 2,4,6-trintrotoluene of a thermoplasticcellulosic resin solidified therein.

2. The castable explosive of claim 1 wherein an organic plasticizer forsaid cellulose resin is also incorporated.

3. The castable explosive of claim 1 wherein said cellulosic resin isselected from the group consisting of cellulose nitrate,

cellulose acetate,

cellulose acetate butyrate,

cellulose propionate,

ethyl cellulose.

4. The castable explosive of claim 3 wherein said cellulosic resin ispresent in an amount between about 0.1 and 2.0 percent by weight basedon the weight of said 2,4,6-trinitrotoluene.

5. The castable explosive of claim 3, wherein said cellulosic resin iscellulose nitrate.

6. In a castable explosive containing 2,4,6- trinitrotoluene possessingoily impurities which cause oily exudation in the solidified cast onstorage, the improvement consisting in the incorporation therein ofabout 0.6 per cent by weight based on the weight of said2,4,6-trinitrotoluene of a thermoplastic cellulosic resin selected fromthe group consisting of cellulose propionate cellulose acetate celluloseacetate butyrate ethyl cellulose cellulose nitrate of high molecularweight and having a nitrogen content of about 12 percent and a viscositybetween about 600 and 1,000 RS seconds.

7. The castable explosive of claim 6 wherein the cellulosic resin iscellulose propionate and a plasticizer selected from the groupconsisting of di-n-hexyl-azelate, dibutyl sebacate and acetylated castoroil is added to prevent brittleness in said explosive due to cellulosepropionate, and an epoxy resinous liquid of the bisphenol type is addedas a heat stabilizer and acid scavenger.

2. The castable explosive of claim 1 wherein an organic plasticizer forsaid cellulose resin is also incorporated.
 3. The castable explosive ofclaim 1 wherein saId cellulosic resin is selected from the groupconsisting of cellulose nitrate, cellulose acetate, cellulose acetatebutyrate, cellulose propionate, ethyl cellulose.
 4. The castableexplosive of claim 3 wherein said cellulosic resin is present in anamount between about 0.1 and 2.0 percent by weight based on the weightof said 2,4,6-trinitrotoluene.
 5. The castable explosive of claim 3,wherein said cellulosic resin is cellulose nitrate.
 6. In a castableexplosive containing 2,4,6-trinitrotoluene possessing oily impuritieswhich cause oily exudation in the solidified cast on storage, theimprovement consisting in the incorporation therein of about 0.6 percent by weight based on the weight of said 2,4,6-trinitrotoluene of athermoplastic cellulosic resin selected from the group consisting ofcellulose propionate cellulose acetate cellulose acetate butyrate ethylcellulose cellulose nitrate of high molecular weight and having anitrogen content of about 12 percent and a viscosity between about 600and 1,000 RS seconds.
 7. The castable explosive of claim 6 wherein thecellulosic resin is cellulose propionate and a plasticizer selected fromthe group consisting of di-n-hexyl-azelate, dibutyl sebacate andacetylated castor oil is added to prevent brittleness in said explosivedue to cellulose propionate, and an epoxy resinous liquid of thebisphenol type is added as a heat stabilizer and acid scavenger.